Getting Older and Weight Loss

I just turned 30 about 6 months back and I had always heard that as you get older its harder to lose weight. I have always been big into fitness but I was always bad at "stick-to-it-iveness" and would never go with perfect eating and lifting for over 4 weeks. I normally thereafter might put on 10lbs but I could easily drop those 10 again in about 2 weeks of doing everything right again. I'm 6'2" and after being a fatty in high school dropped down to 195. I hovered within 5 lbs of that up and down for almost a decade. (5lbs up made it hard to fit in my jeans). I then was going into the SEALs and due to malnourishment abroad while training, I dropped down to 183lbs and looked sickly and gaunt. After I came back to the US for a month, within 30 days I ballooned up to 215lbs. I managed to drop down to 205lbs with my old routine but my body refused to go below 204lbs. However, I still wore the same stuff as when I was 195lbs and visibly looked the same for the most part except a more developed chest (yay for all those push-ups!).

Anyway, due to recent medical reasons, I had to be oafish for almost 2 months recently and got up to 215lbs. again. So I started up my routine again and have been eating perfectly going on my fourth week now and...... I'm almost 220lbs. I'm STILL wearing the same size clothes (as 195lb days) and have my "V" back. I have never gained weight from this routine. I look markedly skinnier though and fit into things better than I did before I started. I am beyond confused by this and although I don't look it, I feel very odd describing myself to people as 6'2" 220lbs. People are saying to me that I'm building muscle far faster than I am losing weight but.... I highly doubt I gained 5lbs of muscle in 3 weeks. I'm guessing the weight just isn't coming off as easy due to my age? I would love to hear theories on this one because I feel like I just don't know my body anymore!

Just to clarify, when I say routine I don't mean I've been doing the same thing since the dawn of time as far as each workout but rather I mean in general the amount I work out has been consistent across the decade+.

Cardio in the morning on an empty stomach (currently Insanity)
Push-ups at Noon before lunch
Lifting after work followed by 20 minutes of intense cardio.

Diet is always pretty much the same, eat 6 times a day (calories are appropriate for training level), protein intake just above my weight minus fat %, no carbs in dinner, small protein intake before sleep, no food with artificial additives (except whey protein powder).

Try improving the way your body burns calories on a molecular level. The body produces less key nutrients as we grow older, including CoQ10 and L-carnitine. This would be a good place to start, and these will also offer many other health benefits.

You built your muscles up to amount X. You lost 5 pounds of muscle to put you down to X-5 pounds of muscle. But your body still remembers up to X. So you conceivably gained back that 5 pounds of muscle very very fast. This has happened to me several times when I have gone from fit to not fit and back again. You get to your previous peak extra fast.

Your metabolism WILL drop over time. And drop and drop and drop. For me, it dropped substantially at ages 33, 37, 45, and 49. Maybe the ages are not exact anymore, but the idea is same amount of calories changes from weight loss to not weight loss - or from weight maintenance to weight gain. This will happen continually, from what I can tell, from somewhere in the 30s until death.

You built your muscles up to amount X. You lost 5 pounds of muscle to put you down to X-5 pounds of muscle. But your body still remembers up to X. So you conceivably gained back that 5 pounds of muscle very very fast. This has happened to me several times when I have gone from fit to not fit and back again. You get to your previous peak extra fast.

Your metabolism WILL drop over time. And drop and drop and drop. For me, it dropped substantially at ages 33, 37, 45, and 49. Maybe the ages are not exact anymore, but the idea is same amount of calories changes from weight loss to not weight loss - or from weight maintenance to weight gain. This will happen continually, from what I can tell, from somewhere in the 30s until death.

That's not a bad theory at all. It would make sense as I got back up to my muscular performance in the gym in just 2 weeks and now its challenging again to put on more weights. As far as the "over training" theories above, I get plenty of carbs; I just don't eat them at night with dinner as your metabolism slows down at that time. What I don't get is where this 20-25lbs is hiding as I'm still wearing the same size clothing at 220 that I was at 195.

As we get older, the most important thing we must work on is our eating habits. Nutrition becomes a bigger key factor in weight loss and weight gain as we age past our 30s. Of course, it is necessary to work out because a body in motion stays in motion.